Offset printing method



Jan- 16" 1934- w. F. WALLACE ET AL v l1,943,645

OFFSET PRINTING METHOD Filed may 11, 1932 `DEB/TJ DATE Z n Z D55/ 7a Durf Patente-1 Jan. 16', 1934 PATENT oFFicE OFFSET PRINTING METHOD Walter F. Wallace, Winnetka, and Lowry K. Grulee, Evanston, Ill., assignors to The Wallace- Press, Chicago, Ill., a corporation of Illinois Application May 11, 1932. Serial No. 610,531

5 Claims. (Cl. 95--5) This invention relates to printing and more particularly to the oiset printing of rule sheets, such as bookkeeping and account forms.

Heretoiore it has been customary to pen rule 5 bookkeeping or account'forms where fine lines and accurate work is required, and thenprint the headings thereon. Pen ruling is relatively slow and requires special machines different from the usual printing machines. Therefore, two kinds of machines must be available for pen ruled forms. Therefore,` forms requiring less accuracy, particularlywhere the thickness and continuity oi the lines is not of prime importance, have been made by contact printing and some by offset printing. However, in such printing the lines become gradually thicker and cannot be controlled with suflicient accuracy, even at the rstprinting, to produce the fine gradeof Work 'accomplished by pen'ruling.

It is the purpose of this invention to make it possible to print ruled or lined forms of at least equal qualitylto-forms as previously produced by pen ruling by offset printing methods and by the usual presses and equipment employed therewith.

vention and the inherent advantages thereof from the following description given in connection with the drawing in which:

Fig. l represents a form to be reproduced known as the copy l Fig. 2 represents the copy as prepared for photographing;

Fig. 3 represents a photoplate looking at the emulsion side, thelpl'ate being of course negative whereas the copy is positive; for convenience in drawing, that which would appear white on the actual negative is shown black and viceversa.

Fig. 4 is a similar View of the photoplate as preparedior further use; and illustrated as in Figure 3. v

Fig. 5 representsthe zinc plate made from the photoplate shown in Fig. 4, the zinc plate being of course positive and from which a similar positive on paper may be reproduced in an offset printing machine in the usual manner.

In the illustrative example shown in the drawing our improved step in the offset printing process is concerned particularly with the treatment of the original copy of ruled forms, wherein such copy usually has iinely. ruled lines in pale color or of such a low degree of actinicism that the lines are completely lost during the photographic step of the process or appear indistinctly on thev negative. In such a case the negative must be retouched and the lines or rulings cut in there- A better understanding will be' had of our inupon. Our improved method of exactly reproducing such original copy embodies the step of marking the lines on the copy with. relatively heavy spots thatP are certainto be transmitted Ato the negative whereby the exact location of the lines or rulings to be cut in upon the negativeare indicated, such spots or markings being used as guides fory the retouchingl or cutting in operation.

In following the method of our invention the copy 1, which is to be reproduced and which is illustrated in Fig. l, is prepared as illustrated in Fig. 2 by spot marking the margins as at 2, preferably with ar black ink to indicate the positions of the lines. The reason for this is that in photo. 70 graphing the copy, the light lines, usually blue, of the ruled forms have such a low actinic value that they do not photograph. The copy thus prepared is photographed in the usual4 manner upon a photoplate or film 3 as illustrated in Fig. 3. 75 As previously stated, the light ruled or printed lines do not photograph and accordingly only the y.printed headings and the spot markings placed upon the edges or margins of the copy shown as at 2a appear on the photographic plate. If the lines do show faintly throughout thephotoplate, it is preferable to obliterate them; usually, however, this is not necessary. The photoplate 3 is then prepared by replacing the ruled lines by scratching or cutting in the lines connecting the marginal points 2a by means of a stylus. The lines can be made of any desired fineness according to the stylus used and the photoplate will then appear as shown in Fig. 4. The photoplate is of course negative, looking at the emulsion side as is shown in both Figs. 3 and 4 and that which appears black in the drawing would actually appear white on the negative, the white of the drawing actually appearing black. The photoplate thus prepared is used in the usual manner in photolithography as the medium from which the zinc plate 4 (Fig. 5) is made, the zinc plate being of course positive to be used in an oiset press. The zinc plate is then placed upon the usual offset printing press orlplanograph by means of duced by using the usual oiset printing and photolithographic apparatus. The photoplates may of course be preserved and any number of zinc plates made therefrom as occasion demands without re-photographing and with consistently thin and accurate lines. Ruled forms may accordingly be made by anyone equipped to do photolithographing and offset printing, i. e., it is not necessary to have special pen ruling machines.

1. The method o f `printing ruled frms which comprises the steps of applying relatively heavy markings to emphasize the position of certain ing a positive plate from said negative, and odset printing reproductions of said copy from said positive plate.

3. In the process of oii'set printing-the step of preparing the photo-negative oi' the copy which consists in spot marking the copy so as to locate on the negative portions of the copy that cannot be transferred photographically and thereby guide retouching of the negative.

4. In the process of reproducing ruled forms by 'oiset printing, the step of preparing a. photonegative of the copy which consists in spot marking certain lines on the copy to assure that portionsthereof appear on the negative and then cutting in such lines on the negative using such markings as guides. g

5. In the process of reproducing finely ruled forms by offset printing, the step of applying relatively heavy guide markings to the copy to emphasize the position of the rulings thereon whereby such markings will appear on the photonegative of the copy to indicate the relative positions of the rulings, and then cutting in the complete rulings upon the negative.

WALTER F. WALLACE. LoWRY K. GRULEE. 

